334 CLINICAL APPLIED ANATOMY. 



The middle group of thoracic glands is called peritracheo- 

 bronchial, and is by far the most important. It lies at the 

 junction of the superior and posterior mediastina, and on 

 account of the practical importance of its relations, is divided 

 into four sub-groups, although these are continuous with each 

 other. The groups comprise (1) the glands around the right 

 bronchus, (2) the glands around the left bronchus, (3) the glands 

 which lie in the bifurcation of the trachea, and (4) the glands 

 which follow the bronchi into the lungs and are embedded in 

 the pulmonary tissue. 



The glands around the right bronchus are wedged in between 

 the termination of the trachea and the lung. When enlarged 

 they may press upon the superior cava which lies in front of 

 them, or the azygos vein which arches over them, or the vagus 

 which passes down behind them. They are not far removed from 

 the right pulmonary artery, and, extending as high as the con- 

 cavity of the subclavian artery, they are favourably situated to 

 compress the right recurrent laryngeal nerve, which turns round 

 that vessel. 



The glands around the left bronchus occupy a corresponding 

 position to those around the right. They extend upwards into 

 the concavity of the aortic arch to reach the left recurrent 

 laryngeal nerve, whilst the vagus is behind them. Both these 

 nerves and also the pulmonary artery may be compressed by 

 enlargement of this sub-group. 



The glands in the bifurcation of the trachea abut upon the 

 pericardium, which separates them from the back of the left 

 auricle. The posterior pulmonary plexus and the oesophagus lie 

 behind them. These glands, when infiltrated with malignant 

 growth, have invaded the pericardium and have compressed the 

 oesophagus. 



The bronchial glands which follow the air tubes into the lung 

 may be traced as far as the fourth sub-divisions of the bronchi. 

 Disease of these glands may be mistaken for primary disease in 

 the lung tissue. 



The enlargement of certain external groups of lymphatic 



